BUFFERED PEPTONE WATER

Specifications

Ingredient g/L
Proteose peptone 10.00
Sodium chloride 5.00
Disodium phosphate 3.50
Monopotassium phosphate 1.50
Final pH (at 25°C) : 7.2 + 0.2

Directions
Suspend 20.00 grams in 1000 ml distilled water. Heat if necessary, to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. If desired, aseptically add rehydrated contents of 1 vial of ECO157: H7 Selective Supplement for isolation of Escherichia coli O157 from foods to previously molten and cooled to 45-50°C medium. Mix well and dispense into sterile tubes or flasks as desired.

Principle
The media contain proteose peptone as a source of carbon, nitrogen, vitamins and minerals. Sodium chloride maintains the osmotic balance and phosphates buffer the medium.

QC Tests
(I) Dehydrated Medium
Colour : Cream to Pale yellow
Appearance : Homogeneous Free Flowing powder
(II) Rehydrated medium
pH (post autoclaving/heating) : 7.2 ± 0.2
Colour (post autoclaving/heating) : Light yellow to light amber
Clarity (post autoclaving/heating) : Clear
(III) Q.C. Test Microbiological
Cultural characteristics observed after 18 –24 hrs at 35-37°C..(Recovery is carried out using XLD Agar,361)
MICROORGANISM (ATCC ) GROWTH
Salmonella enteritidis (13076 ) Good-luxuriant
Salmonella typhi (6539 ) Good-luxuriant
Salmonella typhimurium (14028 ) Good-luxuriant
Escherichia coli 0157:H7 (NCTC 12900) Good-luxuriant (Recovery on tryptone soya broth)

Use
Used as pre -enrichment mediumincreasing the recovery of injured Salmonella species
from foods prior to selective enrichment and isolation.

Storage
Dehydrated medium- below 30°C Prepared medium– Between 2 to 8°C